Journal of Dental Medicine

Statement of Problem: Today, cross infection control is an integral part of dentistry and many dental health care workers no longer question its necessity. All dental equipments and instruments could be potentially considered as a source of infection.

Purpose: The aim of this study was the evaluation of aerobic contaminations of four disposable materials used in routine dental practice.

Materials and Methods: In this cross-sectional study, random sampling was performed and tryptone soy broth transfer culture medium was used. After 24 hours of incubation, samples were transferred to specific culture media. (Mckangy, Chocolate agar and Blood agar). Cultured bacteria were stained and studied using gram staining method. The study was carried out in a 17 weeks period.

Results: All suction tips were infected with Bacillus cereus bacterium. Two cases of cotton roll samples showed contamination with Bacillus cereus, 2 cases with gram positive, coagulase negative cocci, 1 case with Streptococcus viridians and one case with Enterobacter class A. One case of anesthetic cartridges was contaminated with Staphylococcus epidermidis and two cases with Streptococcus viridians. Two cases of gutta-percha samples were contaminated with Bacillus cereus.

Conclusion: Based of the findings of this study, the highest level of contamination was observed in saliva ejector tips. Contamination with Bacillus cereus was seen more frequently.

Statement of Problem: Blood contamination is a common problem in dentistry that can decrease bond strength dramatically which may be affected by methods of decontamination as well.

Purpose: The aim of this study was to evaluate and compare the influence of blood contamination on shear bond strength of composite and compomer to dentin using Prompt L-Pop as an adhesive system. Also, to assess the effectiveness of different surface treatments on the bond strength.

Materials and Methods: In this experimental study, 120 molar teeth were sectioned to provide flat occlusal dentinal surfaces. Specimens were embedded in acrylic resin with the flat surface exposed. The dentinal expose surfaces were polished to 600 grit. The teeth were randomly divided into five groups of twelve specimens (F1–F5) for compomer material and five other groups (Z1- Z5) for composite resin. After application of Promt L-Pop to dentinal surfaces of specimens, the surfaces in all groups, except for F1 and Z1, (as controls) were contaminated with human blood and then one of the following surface treatments was applied. Groups F2 and Z2 without any treatment, groups F3 and Z3 rinsing with water, groups F4 and Z4 rinsing with water and reapplication of adhesive, groups F5 and Z5 rinsing with NaOCl and using Prompt L-Pop again. Restorative materials were applied to treated surfaces using plastic molds. After thermocycling, shear bond strengths, mode of failures and morphology of dentin-material interfaces were evaluated. The data were statistically analyzed using Factorial analysis of Variance, One-Way ANOVA, Duncan, T-student and Chi-Square tests with P<0.05 as the limit of significance.

Results: Compomer showed statistically significant higher bond strength in comparison to composite (P<0.001). Duncan test showed significant differences between all compomer groups, except between groups F4 and F5, and between all composite groups except for groups Z1 and Z4 and for groups Z2 and Z3.

Conclusion: Based on the findings of this study, shear bond strength of compomer material was significantly higher than composite. Blood contamination reduced bond strength, but rinsing contaminated dentin with water or NaOCl and reusing Prompt L-Pop increased bond strength in both materials.

Background and Aim: Pit and fissure sealant therapy, is one of the most effective methods, in prevention of occlusal caries. Saliva contamination before curing the resin can increase the risk of failure in this method. The purpose of this study was to evaluate the effect of saliva contamination prior to curing on microleakage of pit and fissure sealants.

Materials and Methods: In this experimental in vitro study 21 sound human pre molars were selected and two standardized V-Shaped fissures were prepared on both buccal and lingual surfaces, then they were randomly divided into two equal groups. In the control group, the sealant was cured without any saliva contamination and in the case group, the sealed teeth were immersed in artificial saliva for ten seconds before curing. After thermocycling the samples were immersed in 2% fouchsin solution for 24 hours and then sectioned longitudinally in bucco - lingual direction. The specimens were then fixed and assessed under stereomicroscope to determine microleakage and dye penetration using paired student t. test. P<0.05 was considered as the level of significance.

Results: Analysis of data showed no significant differences in microleakage, between the two groups (p=0.178).

Conclusion: According to the results of this study saliva contamination of uncured sealant had no influence on microleakage.

Background and Aim: One of the unique properties of MTA is its setting ability in presence of moisture. The sealing ability of MTA used as a root-end filling was shown to be unaffected by the presence of blood, in vitro. It has been recommended that, because of MTA ability to set in the presence of blood, there is no need to dry the perforation site before MTA placement. On the other hand, based on an in vitro study, it is recommended that hemorrhage be controlled at the perforation site and blood be removed from the perforation walls before placement of tooth-colored MTA. Blood contamination may also affect the crystalline structure of MTA. The microhardness of a material is influenced substantially by some fundamental properties of the material such as crystal structure stability. Thus, it can be used as an indicator of the setting process. It can also indicate the effect of various setting conditions on the overall strength of a material. The aim of this study was to evaluate the effect of blood contamination on microhardness of white and gray MTA as an indicator of their setting process.

Materials and Methods: In groups 1 and 2 each material has been mixed with distilled water according to manufacturer^,s instruction (No contamination groups). In groups 3 and 4 samples were prepared like groups 1 and 2 but the surface of material placed in contact with blood (Surface blood contamination groups). Samples of groups 5 and 6 were mixed with blood instead of distilled water and also the surfaces of the materials were placed in contact with blood (Mixed with blood groups). All samples were stored in 37⁰C and 100% humidity for 96 hours. The microhardness of the samples was measured with Vickers test.

Results: White MTA samples which have not contaminated with blood had the highest microharness (59.9±11.4 N/mm²) while gray MTA mixed with blood had the lowest hardness (18.45±7.8 N/mm²). One-way ANOVA test showed that contamination with blood significantly reduces the microhardness of both white and gray MTA (p<0.001). The difference between white MTA and gray MTA was significant in groups of no contamination (p<0.001), surface blood contamination (p=0.043), and mixed with blood (p<0.001) according to T-Test analysis. In all of them white MTA had higher hardness than gray MTA.

Conclusion: According to results of our study we recommend that hemorrhage should be controlled and any blood contamination should be removed before placement of both white and gray MTA.

Background and Aim: Since the clinical studies conducted to explore the effect of bonding agents on the success of fissure sealant are limited in number, the present study was conducted to compare the effects of two bonding agents on the success of fissure sealant of the saliva- contaminated teeth.

Materials and Methods: In this study, 63 teeth of 35 students aged 6-8 with healthy and newly-erupted upper jaw molar teeth, were selected and divided into two groups. In one group, single-bond and In the other, SE bond were used. As the teeth were newly erupted and the distopalatal area being in contact with the gingival sulcus and this fact that, this area was impossible to isolate, the distal sulcus of the contaminated teeth and the mesial area capable of adequate isolation were assumed isolated. For each group, after etching, the teeth on one side were treated with a sealant and the teeth on the other side were first bonded and then treated with the sealant. Hence, four groups were formed: bonded/isolated, bonded/contaminated, controlled/isolated and controlled/contaminated for any bonding agent. The results of the treatment were assessed in terms of the success and failure and then analyzed using Mc Nemar, and Chi-square tests and Cochran.

Results: The results of the study indicated that:1. Saliva contamination caused a significant increase in sealant failures(p<0.05).2. Use of the two bonding agents significantly increased the success of the sealant(p<0.05).3. Use of the two bonding agents significantly increased the success of the fissure sealant on the saliva-contaminated teeth, even more than when the teeth had been isolated and with only fissure sealant(p<0.05). 4. For the contaminated enamel, the results of SE bond were better than those of the single bond (p<0.05). However, in isolated condition the results of using single bond were better (p<0.05).

Conclusion: The results of the study supported the use of these two bonding agents in the treatment of fissure sealants under both isolated and contaminated conditions. Further, more SE bond seemed to be less sensitive to saliva contamination.

Background and Aims: Moisture contamination of etched enamel during application of sealant is the most frequently cited reason for sealant failure. In previous studies, some hydrophilic bonding agents have been shown to bond to etched enamel after salivary contamination. The purpose of this study was to evaluate the enamelsealant interface following the use of primer on the saliva contaminated and/or moist etched enamel.

Materials and Methods: 40 extracted human incisors were selected. The enamel surfaces were etched for 20 seconds with an acid gel and rinsed for 30 seconds and dried until chalky surface was observed. Teeth were randomly divided into four treatment groups (n=10). Sealant (Deguseal mineral, Degussa) was applied on (1) etched enamel surface as a standard control group, (2) in conjunction with using primer material on moist etched enamel, (3) in conjunction with using primer material on salivary contaminated etched enamel, and (4) on wet contaminated etched enamel surface as a negative control group. Then, the specimens were observed with scanning electron microscopy (SEM) at ×1400 magnification. To evaluate the enamel resin interface, the number of resin tags was counted. Data were analyzed using one-way ANOVA.

Results: The results showed that primer used on moist enamel under sealant had no significantly difference in number and shape of tags in comparison with standard group (P>0.05). Application of primer on saliva contaminated enamel surface under sealant significantly reduced the number of tags and changed the shape and pattern of tags (P<0.001). Following application of sealant on contaminated and etched enamel alone, no resin tags formed.

Conclusion: Application of primer relatively reduced sensitivity to saliva contamination but the pattern was changed and number of tags reduced. Therefore, primer application might be useful whenever the isolation is not possible. However, it should be emphasized that restrict isolation in sealant therapy is recommended.